Network address translation router for voice over internet protocol system

ABSTRACT

A network address translation (NAT) router for connecting an inside network to an outside network. The inside network uses local addresses and has a plurality of voice over Internet protocol (VOIP) systems and a plurality of hosts, and the outside network uses global addresses. An Ethernet driver is connected to Ethernet drivers in the voice over Internet protocol systems by a hub. An Ethernet and Internet protocol (IP) interface module assigns predetermined physical addresses to the Ethernet drivers of the voice over Internet protocol systems. A transmission control protocol/Internet protocol (TCP/IP) module is connected to the Ethernet and Internet protocol interface module and sets a predetermined number of local Internet protocol addresses for the voice over Internet protocol systems. A network address translation module translates an inside local Internet protocol address within a voice over Internet protocol system to a global Internet protocol address.

BACKGROUND OF THE INVENTION

[0001] 1 Technical Field

[0002] The present invention relates generally to a voice over Internetprotocol (VoIP) system, and in particular, to a voice over Internetprotocol system that assigns addresses through network addresstranslation.

[0003] 2 Related Art

[0004] Voice over Internet protocol (VoIP) is a novel communicationsservice that provides a voice call not over the public switchedtelephone network (PSTN) but over the Internet. Due to the use of apacket-based network, domestic/international calls can be made free ofcharge by deploying voice over Internet protocol. Voice over Internetprotocol can even deliver video information as well as audio informationusing the ITU-T H.323 protocol.

[0005] A voice over Internet protocol (VOIP) system includes theInternet as a backbone. Gateways and personal computers (PCs) areconnected to the Internet. The gateways are connected to public switchedtelephone networks that are in turn connected to telephones. Thetelephones and the personal computers are endpoints that are capable ofcarrying out communications by voice (mandatory), moving pictures(optional), and data (optional) in one-to-one communications or videoconferencing. These terminals can carry out real-time bi-directionalcommunications with the gateways or other terminals. The gateways enablereal-time bi-directional communications between terminals (e.g.,personal computers) connected to the Internet (that is, the packet-basednetwork) and terminals (e.g., telephones) connected to the publicswitched telephone networks or an integrated services digital network(ISDN).

[0006] The voice over Internet protocol system must use a uniqueInternet protocol (IP) address to communicate over the Internet.However, permanent assignment of unique Internet protocol addresses forconnection to the global Internet results in a shortage of availableunique Internet protocol addresses.

[0007] To solve the above problem, network address translation (NAT) isused. Network address translation is a technology which allows all ofthe hosts on a private network to access the Internet via a singlepublic Internet protocol address by translating a plurality of temporaryinside addresses to the public Internet protocol address. The resultingavoidance of collisions with outside Internet protocol addresses enablesuse of more inside Internet protocol addresses than regulated.

[0008] In such a network, transmission control protocol/Internetprotocol (TCP/IP)-based data coexists with voice over Internet protocol(VoIP)-based voice. Despite use of the same transmission controlprotocol/internet protocol network layer, network address translationdoes not support existing protocols used for general data for the voiceover Internet protocol. Moreover, most networks provide control only togeneral data internally, and exclude voice data. Since the voice overInternet protocol system can access the Internet by a unique Internetprotocol address only, as compared to general private network systems,Internet protocol efficiency of the voice over Internet protocol systemis low.

[0009] The following patents are considered to be generally pertinent tothe present invention but are burdened by the disadvantages set forthabove: U.S. Patent Publication No. 2001/0043571A1 to Jang et al.,entitled MULTIPLE SUBSCRIBER VIDEOCONFERENCING SYSTEM, published on Nov.22, 2001; U.S. Patent Publication No. 2001/0004361 A1 to Kobayashi,entitled TELEPHONE CONTROLLER FOR VOIP, published on Jun. 21, 2001; andU.S. Patent Publication No. 2001/0030950 A1 to Chen et al., entitledBROADBAND COMMUNICATIONS ACCESS DEVICE, published on Oct. 18, 2001.

SUMMARY OF THE INVENTION

[0010] It is, therefore, an object of the present invention to provide asystem for maximizing voice over Internet protocol efficiency byapplying a net protocol to a voice over Internet protocol system.

[0011] To achieve the above and other objects, there is provided anetwork address translation (NAT) router for connecting an insidenetwork to an outside network. The inside network uses local addressesand has a plurality of voice over Internet protocol (VoIP) systems and aplurality of hosts, while the outside network uses global addresses. AnEthernet driver is connected to other Ethernet drivers in the voice overInternet protocol systems by a hub. An Ethernet and Internet protocolinterface module assigns predetermined physical addresses to theEthernet drivers of the voice over Internet protocol systems. Atransmission control protocol/internet protocol module is connected tothe Ethernet and Internet protocol interface module, and sets apredetermined number of local Internet protocol addresses for the voiceover Internet protocol systems, while a network address translationmodule translates an inside local Internet protocol address within thevoice over Internet protocol system to a global Internet protocoladdress.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete appreciation of the invention, and many of theattendant advantages thereof, will be readily apparent as the samebecomes better understood by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings in which like reference symbols indicate the same or similarcomponents, wherein:

[0013]FIG. 1 is a schematic view illustrating the configuration of atypical voice over Internet protocol (VoIP) system;

[0014]FIG. 2 is a schematic view illustrating the configuration of anetwork using network address translation (NAT) for voice over Internetprotocol (VOIP) according to the present invention; and

[0015]FIG. 3 is a block diagram of the voice over Internet protocol(VoIP) system and the router illustrated in FIG. 2 according to thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] A preferred embodiment of the present invention will be describedbelow with reference to the accompanying drawings. In the followingdescription, well-known functions or constructions are not described indetail since they would obscure the invention in unnecessary detail.

[0017]FIG. 1 illustrates a voice over Internet protocol (VoIP) systemusing the Internet as a backbone. Referring to FIG. 1, the voice overInternet protocol system includes the Internet 8 as a backbone. Gateways6 and 10 and personal computers (PCs) 16 and 18 are connected to theInternet 8. The gateways 6 and 10 are connected to public switchedtelephone networks 4 and 12, respectively, which in turn are connectedto telephones 2 and 14, respectively. The telephones 2 and 14 and thepersonal computers 16 and 18 are endpoints that are capable of carryingout communications by voice (mandatory), moving pictures (optional), anddata (optional) in one-to-one communications or video conferencing.These terminals can carry out real-time bi-directional communicationswith the gateways 6 and 10 or other terminals. The gateways 6 and 10enable real-time bi-directional communications between terminals (e.g.,the personal computers 16 and 18) connected to the Internet 8 (that is,the packet-based network) and terminals (e.g., the telephones 2 and 14)connected to the public switched telephone networks 4 and 12 or anintegrated services digital network (ISDN).

[0018] The voice over Internet protocol system illustrated in FIG. 1must use a unique Internet protocol (IP) address to communicate over theInternet. However, permanent assignment of unique Internet protocoladdresses for connection to the global Internet results in a shortage ofavailable unique Internet protocol addresses.

[0019] Referring to FIG. 2, the term “inside” denotes a private networkfor which Internet access is allowed by address translation, and theterm “outside” denotes an external network, usually the Internet. Avoice over Internet protocol system 20 and a personal computer 30 areconnected to a router 40, which is connected to the Internet 50, andpersonal computers 60 and 70 are also connected to the Internet 50.Network address translation can be set only in a router that connectstwo networks. The voice over Internet protocol (VoIP) system 20 and thepersonal computer 30 use private addresses or invalid Internet protocol(IP) addresses. They can transmit packets to the Internet 50 only if theprivate addresses are translated to public Internet protocol addresses.The address translation interacts with routing by setting networkaddress translation (NAT) in the router 40 at an intended location.Network address translation is implemented using routing tables in whichprivate Internet protocol addresses are mapped to public Internetprotocol addresses. In general, each routing table has networkaddresses, sub-net addresses, or the Internet protocol addresses ofdevices.

[0020] The router 40 has typical network address translation routerfunctionalities, that is, fixed address translation, dynamic sourceaddress translation, dynamic port translation, and destination addressrotary translation. An internal local address is mapped to a globaladdress on a one-toone basis by fixed address translation. By means ofdynamic source address translation, an internal local address can bedynamically mapped to a global address.

[0021] Dynamic port translation is carried out using a transmissioncontrol protocol (TCP)/user datagram protocol (UDP) source port toconserve addresses in an address pool. Even though a plurality of localaddresses is mapped to a single global address, port numbers can bediscriminated. Destination address rotary translation allows particulartraffic to be carried from the outside to the inside.

[0022] The router 40 sets a desired number of voice over Internetprotocol (VoIP) local Internet protocol addresses for the voice overInternet protocol system 20. Then, the router 40 assigns a particularInternet protocol address to voice over Internet protocol, and allowsInternet access by translating the Internet protocol address to theglobal Internet protocol address.

[0023]FIG. 3 is a block diagram of the voice over Internet protocol(VoIP) system 20 and the router 40 illustrated in FIG. 2. Referring toFIG. 3, outgoing Internet protocol (IP) packets related to voice overInternet protocol pass through the router 40, and incoming voice overInternet protocol packets also pass through the router 40 so as to reacha voice over Internet protocol main controller 22. An Ethernet driver 24in the voice over Internet protocol system 20 is operated in conjunctionwith an Ethernet driver 48 in the router 40 by means of a hub (notshown). The hub is a device that connects equipment at an office toequipment located a short distance away in a local area network (LAN).In general, the hub performs network connection with computers orprinters, connection to another network (or another hub) located a shortdistance away, and connection to a network device such as a router,network status checker, and signal amplification unit. The Ethernetdriver 24 can be used independently in the voice over Internet protocolsystem 20, or in connection with the router 40. The Ethernet driver hasa medium access control (MAC) address for physical connection to anetwork. In the present invention, a predetermined medium access controladdress is assigned to voice over Internet protocol.

[0024] A particular Ethernet port number received from the Ethernet isdelivered from an Ethernet and Internet protocol (IP) interface module46 directly to a transmission control protocol/Internet protocol(TCP/IP) module 44. The transmission control protocol/Internet protocolmodule 44 assigns a local address set by a user to voice over Internetprotocol (VoIP) using conventional network address translation (NAT), orsets a desired number of voice over Internet protocol local Internetprotocol addresses.

[0025] A network address translation module 42 transmits data topersonal computers and network devices by translating a global Internetprotocol address to local Internet protocol addresses. Thus, the networkaddress translation module 42 can use up to 255 local Internet protocoladdresses. The network address translation module 42 assigns aparticular Internet protocol address to voice over Internet protocol(VoIP), and transmits voice data without any limitations. That is, thenetwork address translation module 42 can translate an inside localInternet protocol address in the voice over Internet protocol system 20to an outside global Internet protocol address. When voice and data aretransmitted 3:1, voice efficiency is increased in the present invention.

[0026] In accordance with the present invention, the cost associatedwith Internet protocol address assignment is reduced and voice packetsare processed with high efficiency by applying an NET protocol to voiceover Internet protocol (VoIP). Therefore, a stable network system can berealized. In particular, operation of a plurality of voice over Internetprotocol systems can maximize cost reduction.

[0027] Although a preferred embodiment of the present invention has beendescribed, it will be understood by those skilled in the art that thepresent invention should not be limited to the described preferredembodiment. Rather, various changes and modifications can be made withinthe spirit and scope of the present invention, as defined by thefollowing claims.

What is claimed is:
 1. A network address translation (NAT) router forconnecting an inside network that uses local addresses and has aplurality of voice over Internet protocol (VOIP) systems and a pluralityof hosts to an outside network that uses global addresses, comprising:an Ethernet and Internet protocol (IP) interface module for assigningpredetermined physical addresses to Ethernet drivers of the voice overInternet protocol systems; a transmission control protocol/Internetprotocol (TCP/IP) module connected to the Ethernet and Internet protocolinterface module for setting a predetermined number of local Internetprotocol addresses for the voice over Internet protocol systems; and anetwork address translation (NAT) module for translating an inside localInternet protocol address within one of the voice over Internet protocolsystems to a global Internet protocol address.
 2. The network addresstranslation router of claim 1, further comprising an Ethernet driverconnected to the Ethernet drivers of the voice over Internet protocolsystems by a hub.
 3. The network address translation router of claim 2,wherein the network address translation module has a routing table thatlists the physical addresses and the inside local Internet protocoladdresses of the voice over Internet protocol systems.
 4. The networkaddress translation router of claim 3, wherein the transmission controlprotocol/Internet protocol (TCP/IP) module assigns the local Internetprotocol addresses to the voice over Internet protocol systems so thatvoice transmission is carried out freely.
 5. The network addresstranslation router of claim 4, wherein the Ethernet and Internetprotocol (IP) interface module delivers an Ethernet port number to thetransmission control protocol/Internet protocol (TCP/IP) module.
 6. Thenetwork address translation router of claim 3, wherein the Ethernet andInternet protocol (IP) interface module delivers an Ethernet port numberto the transmission control protocol/Internet protocol (TCP/IP) module.7. The network address translation router of claim 2, wherein thetransmission control protocol/Internet protocol (TCP/IP) module assignsthe local Internet protocol addresses to the voice over Internetprotocol systems so that voice transmission is carried out freely. 8.The network address translation router of claim 7, wherein the Ethernetand Internet protocol (IP) interface module delivers an Ethernet portnumber to the transmission control protocol/Internet protocol (TCP/IP)module.
 9. The network address translation router of claim 2, whereinthe Ethernet and Internet protocol (IP) interface module delivers anEthernet port number to the transmission control protocol/Internetprotocol (TCP/IP) module.
 10. The network address translation router ofclaim 1, wherein the network address translation module has a routingtable that lists the physical addresses and the inside local Internetprotocol addresses of the voice over Internet protocol systems.
 11. Thenetwork address translation router of claim 10, wherein the transmissioncontrol protocol/Internet protocol module assigns the local Internetprotocol addresses to the voice over Internet protocol systems so thatvoice transmission is carried out freely.
 12. The network addresstranslation router of claim 11, wherein the Ethernet and Internetprotocol interface module delivers an Ethernet port number to thetransmission control protocol/Internet protocol module.
 13. The networkaddress translation router of claim 10, wherein the Ethernet andInternet protocol interface module delivers an Ethernet port number tothe transmission control protocol/Internet protocol module.
 14. Thenetwork address translation router of claim 1, wherein the transmissioncontrol protocol/Internet protocol module assigns the local Internetprotocol addresses to the voice over Internet protocol systems so thatvoice transmission is carried out freely.
 15. The network addresstranslation router of claim 14, wherein the Ethernet and Internetprotocol interface module delivers an Ethernet port number to thetransmission control protocol/Internet protocol module.
 16. The networkaddress translation router of claim 1, wherein the Ethernet and Internetprotocol interface module delivers an Ethernet port number to thetransmission control protocol/Internet protocol module.
 17. A networkaddress translation router for connecting an inside network that useslocal addresses and has a plurality of voice over Internet protocolsystems and a plurality of hosts to an outside network that uses globaladdresses, comprising: an Ethernet and Internet protocol interfacemodule for assigning predetermined physical addresses to Ethernetdrivers of the voice over Internet protocol systems; a transmissioncontrol protocol/Internet protocol module connected to the Ethernet andInternet protocol interface module for assigning local Internet protocoladdresses to the voice over Internet protocol systems so that voicetransmission is carried out freely; and a network address translationmodule for translating an inside local Internet protocol address withinone of the voice over Internet protocol systems to a global Internetprotocol address.
 18. The network address translation router of claim17, further comprising an Ethernet driver connected to the Ethernetdrivers of the voice over Internet protocol systems by a hub.
 19. Thenetwork address translation router of claim 18, wherein the Ethernet andInternet protocol (IP) interface module assigns the predeterminedphysical addresses to the Ethernet drivers of the voice over Internetprotocol (VoIP) systems.
 20. The network address translation router ofclaim 17, wherein the network address translation module has a routingtable that lists the physical addresses and the inside local Internetprotocol addresses of the voice over Internet protocol systems.
 21. Thenetwork address translation router of claim 17, wherein the Ethernet andInternet protocol (IP) interface module delivers an Ethernet port numberto the transmission control protocol/Internet protocol (TCP/IP) module.